Kinetic energy of particles in a substance is directly related to its temperature. The sample with the lowest temperature will therefore have the lowest kinetic energy.
From the table:
- Sample 1: 98.2 °C
- Sample 2: 46.0 °C
- Sample 3: 100.6 °C
- Sample 4: 31.4 °C
Sample 4 has the lowest temperature at 31.4 °C. Therefore, sample 4 has the lowest kinetic energy.
The answer is 4.